How to fix cron jobs issue in magento 2?

Instruction

In my case it was caused by some cron jobs migrated from Magento 1, in core_config_data. Magento 2 expects the format to be crontab/{groupname}/jobs/{code}, while the imported ones miss the group name (i.e. default). If that is your case you might want to delete the wrong entries in core_config_data, or update them to map the new cron jobs.

You might need to remove all crontab entries from core_config_data table and then run php bin/magento setup:upgrade. 

bin/magento ca:fl config 

SELECT * FROM core_config_data WHERE path LIKE 'crontab/%' AND path NOT LIKE 'crontab/default%' AND config_id > 0 I needed last part AND config_id > 0